There have conventionally been devised various types of image display devices such as liquid crystal display devices and PDP (plasma display panel) display devices. Generally, an image display device incorporates a light emitting device for image display that emits light used in image display. By controlling the degree of transmission, intensity, etc. of the light appropriately according to image data fed to it, the image display device displays images.
For example, a liquid crystal display device incorporates a backlight (corresponding to part of the light emitting device for image display mentioned above) and a liquid crystal panel, and the liquid crystal panel controls the degree of transmission of backlight in such a way as to display an image. As such backlights also, various types have been devised.
For example, in one conventionally devised backlight, a plate-form member that is arranged opposite a liquid crystal panel is divided into a plurality of areas (regions), and light emitting elements (such as LEDs) are provided in those areas respectively. For another example, Patent Document 1 listed below discloses a type (hereinafter referred to also as the “area-driven type” for convenience's sake) in which the light emission of light emitting elements provided in different areas respectively is controlled on an area-by-area basis.
Purportedly, with the image display device disclosed in Patent Document 1, it is possible to adjust the luminance of the backlight (in other words, the light emission electric power supplied to the light emitting elements of the backlight) on an area-by-area basis according to image data, and thus it is possible to obtain an image with a high contrast ratio.